The present invention relates to a spacer profile for a spacer frame to be mounted in the marginal area of an insulating window unit, by forming an intermediate space between the panes, with a chamber for receiving hygroscopic materials and with at least one contact web resting on a pane inside on at least one side of the chamber, which is connected with the chamber via a bridge section.
In the sense of the invention, the panes of the insulating window unit are normally glass panes of inorganic or organic glass, without limiting the invention. The panes can be coated or finished in any other way, in order to impart to the insulating window unit special functions, such as increased heat insulating or sound insulating capabilities.
The most important tasks of spacer frames are to space apart the panes of an insulating window units, to insure the mechanical strength of the unit and to protect the space between the panes from external influences. Primarily in insulating window units with high heat insulation, special attention has to be paid to the heat transmission characteristics of the peripheral connection, including the spacer frame and the spacer profiles or frame limbs constituting the same. It has been frequently proven that use of the conventional metallic spacers resulted in a reduction of the heat insulating properties of an insulating window unit. The reduced heat insulation effect appears clearly in the area of the peripheral connection, in the formation of condensation water at the margin of the inner pane at low external temperatures. There are general attempts to eliminate such formation of condensation water even at low external temperatures by keeping the temperature in the area of the peripheral connection at the inner pane as high as possible. Developments in this direction are known under the term of xe2x80x9cwarm edgexe2x80x9d techniques.
In addition to metallic spacer profiles, for quite a long time spacer profiles of plastic materials have been used, thus taking advantage of the low heat conductivity of these materials. However plastic spacer profiles have the disadvantage that they can be bent only with considerable effort or not at all for the production of spacer frames made in one piece. Therefore plastic profiles are cut into straight bars to the size of the respective insulating window unit and interconnected to form a spacer frame by means of several corner brackets. Compared to metal, as a rule such plastic materials also have a low diffusion tightness. Therefore in the case of plastic spacers special measures have to be taken insuring that air humidity existing in the surroundings does not penetrate the intermediate space between the panes to the extent that it depletes the absorption capability of the drying agents normally provided in the spacer profiles, impairing the function of the insulating window unit.
Furthermore a spacer profile has also to prevent the filling gases in the intermediate pane space, such as argon, krypton, xenon, sulfur hexafluoride from escaping. Conversely, nitrogen, oxygen etc. contained in the outer atmosphere should not penetrate the intermediate pane space. Diffusion tightness it applies to vapor diffusion tightness, as well as to gas diffusion tightness for the mentioned gases.
In order to improve the vapor diffusion tightness, DE 33 02 659 A1 proposes to provide a plastic spacer profile with a vapor barrier, by applying a thin metal foil or a metalized plastic foil to the plastic profile on its surface which in assembled state faces away from the space between the panes. This metal foil has to span across the intermediate pane space as completely as possible, insuring the desired vapor barrier effect. The disadvantage here is that the metal foil creates a path of high heat conductivity from one pane of the insulating widow unit to the other. This considerably reduces the effect intended by using a plastic material for the profiles, namely the reduction of heat conductivity of the peripheral connection.
Other spacer profiles, for instance the ones which meet the aforementioned xe2x80x9cwarm-edgexe2x80x9d conditions, use special stainless steels, which in comparison to other metals have a lower heat conductivity, for profile materials. Examples are mentioned in xe2x80x9cGlasweltxe2x80x9d 6/1995, pages 152-155. The spacer frames made thereof consist of one piece and are closed at all corners.
A spacer profile of the kind mentioned at the outset is known from DE 78 31 818 U1. The contact webs, there named flanks, to be connected via a sealing adhesive with the panes of the insulating window unit, form the force application points for a specially designed tool fixing the contact webs during bending. The spacer profile is made in one piece of the same material, presumably a metal, which can be bent at right angles obviously only by means of the indicated procedure. Indications as to heat insulation or even measures for improving the heat insulation can not be found in the publication.
It is the object of the present invention to provide a spacer profile which can be produced on a large scale and at low cost, with high heat insulating characteristics, whereby from such a spacer profile it should be possible to make a one-piece spacer frame, so that when cold or only slightly warmed, the profile will be bendable in such a manner as to avoid deformation. The spacer profile should also be advantageously in a position to permit to a limited extent relative motions of the glass panes as a result of inner pressure or shearing strain.
This object is achieved with a spacer profile in which the profile corpus of the spacer profile is formed by an elastically-plastically deformable material with low heat conductivity and at least the contact web is firmly materially connected with a deformable reinforcement layer.
The profile corpus comprises volumwise the main part of the spacer profile and imparts to the same its cross section profile. It comprises especially the chamber walls, the bridge sections, as well as the contact webs.
Elastically-plastically deformable materials are materials wherein after the bending process elastic restoring forces become active, which is typically the case of plastic materials as to which one part of the bending occurs through a plastic, irreversible deformation.
Plastically deformable materials comprise such materials wherein after deformation practically no elastic restoring forces are active, such as is typical for metals bent beyond their apparent yielding point.
The term xe2x80x9cmaterially connectedxe2x80x9d means that the profile corpus and the plastically deformable layer are permanently connected to each other, for instance through coextrusion of the profile body with the plastically deformable layer, or by separately laminating the plastically deformable layer on it, optionally by means of a bonding agent, or by similar techniques.
Materials with poor heat conductivity or heat-insulating materials are materials which with respect to metals have a clearly reduced heat conduction value, i.e. heat conduction reduced at least by a factor of 10. The heat conduction values xcexare typically of the order of magnitude of 5 W/(mxc2x7K) and below, preferably smaller than 1 W/(mxc2x7K) and even more preferred smaller than 0.3 W/(mxc2x7K).
Surprisingly it has been found that already by reinforcing only the contact webs of the spacer profile made of elastically-plastically deformable material with a plastically deformable reinforcement layer, a good cold bendability of the profile can be achieved. The so-formed sandwich composite produces a high bending resistance moment with the characteristics of the plastic materials and the profile contour. This however results in higher bending forces, but insures only minimal resilience in the bent state, as well as high corner rigidity and yields stiff, and easy to handle spacer frames. The elastic restoring force of the profile body material can therefore act only minimally.
The layer thickness of the reinforcement layer depends on the properties of the actually used materials of the profile corpus and of the reinforcement layer which have to be selected so that, after a bending process, the desired bend is substantially maintained, which means that after a bending by 90xc2x0 the resilience amounts in any case only to a few degrees, i.e. a maximum of 10xc2x0. The reinforcement layer does not have to be a compact layer, but can have for instance netlike perforations.
Preferably the profile body has at least one U-shaped cross section area open towards the outside, whose flanks are formed by a contact web and the neighboring side wall of the chamber and whose base is formed by the bridge sections connecting the same. xe2x80x9cOutsidexe2x80x9d means in this case the side of the profile body facing away for the space between the panes in assembled state.
Further the flanks of the U-shaped cross section area advantageously have a height which is twice, preferably at least three times and further preferably at least 5 times, the width of the base.
In a particularly preferred embodiment of the invention the reinforcement layer is set on the contact surface of the contact web. The contact surface is the surface of the contact web facing the pane inside in the mounted state.
In a further embodiment the reinforcement layer is set on the chamber-side surface of the contact web opposite to the contact surface.
In each embodiment the reinforcement layer extends normally at least over the greater part of the height of the contact web, as well as over its entire length.
Preferably the profile body is permanently connected with a reinforcement layer extending substantially over its entire width and length.
The invention is based on the finding that, in this case, the reinforcement layer contributes to heat conduction from one pane to the other. However, as a result of the contour of the material with low heat conductivity of the profile corpus indicated by the invention, the path of high heat conductivity created by the reinforcement layer is considerably lengthened by comparison with the conventional profiles, so that the heat insulating properties of an insulating window unit equipped with the spacer profile is considerably improved in the area of the peripheral connection due to the invention.
Preferably, especially when the profile corpus material does not offer sufficient diffusion tightness, the reinforcement layer is made to be diffusion tight, at least in the area of the chamber walls and the bridge section, but normally over its entire surface.
Advantageously the reinforcement layer is arranged on the outside of the profile body, or close to the same at least partially embedded in the profile body. Due to the geometric configuration of the reinforcement layer determined by the profile body, an arc-preserving bending resistance moment results, which contributes to the cold pliability without disturbing deformations.
The bending resistance moment can be increased particularly by arranging the reinforcement layer on the chamber-side surface of the contact web on the outside of the bridge section connected with the contact web, as well as on the outside of the chamber side wall adjacent to the contact web, whereby the reinforcement layer has to be diffusion tight at least in the area of the bridge section and the chamber side wall, when additional steps for diffusion tightness are to be eliminated.
It is particularly preferred when the reinforcement layer extends continuously from the contact surface of the contact web over its chamber-side surface, the outside of the bridge section connected with the contact web, the outside of the adjacent side wall of the chamber, as well as the outside of the outer chamber wall, whereby in this case the reinforcement layer has to be diffusion tight at least in the area of the bridge section and side wall of the chamber. Due to the meandering path of the reinforcement layer in this particularly preferred embodiment, a high arc-preserving bending resistance moment is created. This however has stronger bending forces as a consequence, but in the bent state insures a particularly low resilience and a high degree of corner stiffness. Therefore practically the elastic restoring force of the elastically-plastically deformable materials can not become active.
The spacer profile is easy to manufacture, for instance through an extrusion process. After the application of the reinforcement layer, the frame can be made by cold bending. For this purpose conventional bending equipment without significant modifications can be used. A fixing of the contact webs during bending, as in the prior art, is not necessary within the framework of the invention. After the bending process, the contact webs do not show any disturbing deformations.
Advantageously the chamber is arranged centrally in the spacer profile, whereby on both sides of the chamber at least one contact web is provided. This symmetric design makes a positive contribution to the compensation of relative motions of the panes.
The cross section of the chamber can be substantially polygonal, particularly rectangular or trapezoidal. It is also possible to have corner-free, for instance oval configurations of the chamber cross section. It is self-understood that the concept xe2x80x9cchamberxe2x80x9d includes, besides closed hollow spaces, also trough-like profile shapes.
According to an advantageous embodiment, in the spacer profile, the bridge section is secured in one corner area of the chamber for the connection of at least one contact web. It is particularly advantageous for the bending behavior and the heat insulation when the bridge section is fastened on a corner close to the space between the panes. However it is also conceivable to arrange the bridge section for the connection of at least one contact web in the middle area of a chamber side wall, which in the mounted state faces the panes of the window unit.
Depending on the individual configuration, it can be equally advantageous to make the height of the contact web greater than, smaller than or substantially equal to the height of the adjoining side of the chamber. In order to insure a large contact surface on the pane, it can be advantageous to allow the contact webs to project as much as possible beyond the chamber. It also can be advantageous to arrange the contact webs parallel to the side wall of the chamber. Shorter contact webs improve the contact between the mechanically stabilizing sealing means to be applied externally and the panes.
It is however also possible to arrange the contact webs at a positive or negative angle to one side wall of the chamber, which can range for instance between xe2x88x9245xc2x0 to +45xc2x0, in relation to the longitudinal median axis of the chamber cross section. This can improve the spring action of the spacer profile, as necessary.
Also the contact webs can have at least one contact rib. Such a contact rib will normally run orthogonally with respect to the contact web, so that in the mounted state a clear space is defined between the contact web and the inside of the pane.
As materials for the reinforcement layer, which preferably has a heat conduction value xcex less than 50 W/(mxc2x7K), metals with poor heat conductivity such as mainly tin plate or stainless steel, have proven to be suitable. These materials can be for instance in the form of foils permanently applied to the profile corpus of the spacer profile by means of a bonding agent or laminated onto the same. The tin plate is a sheet iron with a tin surface coating. Suitable stainless steel types are for instance 4301 or 4310 according to the German steel standards.
It has proven to be advantageous when, with regard to the strength of the bond between the reinforcement layer and the profile body, a peeling value (force/adhesion width) of xe2x89xa74 N/mm at a 180xc2x0 peeling test exists in the finished product.
The gas and vapor barrier required for the diffusion tightness of the reinforcement layer, in combination with the mechanical behavior sought according to the invention can be achieved when the reinforcement layer using tin plate has a thickness of less than 0.2 mm, preferably 0.13 mm the most. If stainless steel is used, it is possible to have even lesser layer thicknesses, namely less than 0.1 mm, preferably 0.05 mm at the most. The minimal layer thickness should be selected so that the required stiffness of the spacer profile is reached and the diffusion tightness is maintained also after bending, particularly in the bent areas. For the indicated materials a minimal layer thickness of 0.02 mm is required.
Depending on the manner in which the spacer profile is finally integrated in the insulating window unit, it can be advantageous to provide the reinforcement layer on its exposed side sensitive to mechanical and chemical influences at least partially with a protective layer. This can for instance consist of a lacquer or plastic material. It is however also possible to provide the reinforcement layer with a thin layer of the heat-insulating material, respectively the material with poor heat conductivity of the spacer profile and to embed the layer in this material at least in certain areas.
Preferably the path of high heat conductivity formed by the reinforcement layer from one pane to the other is a minimum 1.2 times, preferably more than 1.5 times, preferably more than 2 times, and most preferably up to 4 times the width of the space between the panes.
With regard to the resilience with simultaneous material savings, the spacer profile can be optimized when the clear width between a contact web and the adjacent side wall of the chamber amounts to more than 0.5 mm. Such a minimal distance improves also the bending behavior of the spacer profile and facilitates the insertion of mechanically stabilizing sealing means.
Generally the chamber, bridge section and contact webs are made substantially with the same wall thickness. When it is intended to keep the chamber volume for receiving hygroscopic material as large as possible, then it is possible to reduce the wall thickness of all or only some walls of the chamber.
Suitable heat-insulating materials for the spacer profile have been proven to be thermoplastic synthetic materials with a heat conduction value xcex less than 0.3 W/(mxc2x7K), e.g. polypropylene, polyethylene terephthalate, polyamide or polycarbonate. The plastic material can contain the usual fillers, additives, dyes, agents for UV-protection, etc.
From a spacer profile according to the invention it is simple to produce spacer frames made in one piece for insulating window units, which have to be closed only by one connector. Namely it is possible by using commercially available bending tools to bend the spacer profile into corners, which even in this corner areas are characterized by planar surfaces of the contact webs on the side facing the pane inside in the mounted state. The chamber deformation occurring during bending are absorbed by the space between the chamber side walls and the neighboring contact web. The good pliability of the contact webs, as well as of the spacer profile according to the invention, can be probably explained by the fact that the permanent material bond between the elastically-plastically deformable, heat-insulating material, particularly of synthetic material, and the plastically deformable reinforcement layer, particularly of metal, insures a good balance of forces even during cold bending. However it could still be advantageous to slightly warm the bending point, so that relaxation processes are accelerated. The connector is designed either as a corner connector or, connects as a straight connector the cold-bent spacer profile in a connection area outside the corners, for instance in the middle of a pane edge.
Furthermore the invention comprises an insulating window unit with at least two opposite panes and a spacer frame consisting of a spacer profile as described above, whereby the spacer frame with the panes define an intermediate pane space, wherein the contact webs are bonded substantially over their entire length and height with the inner pane side facing them and wherein the clear space between contact webs and chamber, as well as at least the connection area to the neighboring inner pane side are filled with a mechanically stabilizing sealing material.
According to an advantageous embodiment, in the insulating window unit the mechanically stabilizing sealing material basically fills up entirely the free space to the outer peripheral margin of the window unit. Commercially available insulating glass adhesives based on polysulfide, polyurethane or silicon have proven themselves to be suitable sealing materials. As a diffusion-tight adhesive material for bonding the contact webs with inner pane side for instance a butyl sealing material on a polyisobutylene basis is suitable.